Accident McDonnell Douglas DC-9-31 N9333,
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Date:Tuesday 1 May 2001
Time:14:37
Type:Silhouette image of generic DC93 model; specific model in this crash may look slightly different    
McDonnell Douglas DC-9-31
Owner/operator:Northwest Airlines
Registration: N9333
MSN: 47246/292
Year of manufacture:1968
Engine model:Pratt & Whitney JT8D-9A (HK3)
Fatalities:Fatalities: 0 / Occupants: 42
Aircraft damage: Substantial, repaired
Category:Accident
Location:Minneapolis-St. Paul International Airport, MN (MSP) -   United States of America
Phase: Standing
Nature:Passenger - Scheduled
Departure airport:Minneapolis-St. Paul International Airport, MN (MSP/KMSP)
Destination airport:Philadelphia International Airport, PA (PHL/KPHL)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The DC-9-31, N9333, operated by Northwest Airlines as flight NW682, was substantially damaged when it was struck by an aircraft tug during passenger boarding. The flight was parked at gate D3 at the Minneapolis-St. Paul International/Wold-Chamberlain Airport, Minnesota and was bound for the Philadelphia International Airport, Pennsylvania. No injuries were reported. The driver of the tug and a food service worker received minor injuries.
The aircraft was parked and was being prepared for departure by various ground workers including the tug driver and workers restocking the aircraft food supply. The driver of the tug said that he was moving the vehicle into position in order to connect the aircraft tow bar in preparation for pushback. He said that when he placed the tug into gear, it lurched forward into the parked aircraft. He said that pieces of the aircraft protruded through the windshield of the vehicle and pinned him into his seat. He said that he was unable to shift the vehicle into reverse and his leg was pinned on the accelerator pedal. Other ground workers in the area attempted to shut off the tug's engine. The driver said that the vehicle continued to drive forward until the engine was finally shut off. During the event, the pilot of the aircraft had applied the brakes when he noticed the unplanned movement of the airplane. The aircraft was pushed backward about 30 feet causing damage to the nose section of the fuselage. A food service worker was injured when he jumped from his vehicle which was parked next to the aircraft.

Subsequent to the accident, the tug was placed on jacks and a check performed. During the check it was found that the normal engine shutoff switch would not shut the engine off if the engine was operated at high throttle settings. It was further discovered that at high throttle settings, the brake system was not able to stop the rotation of the drive wheels. No anomalies were found during this test that would explain the lurching described by the tug driver. Subsequent to the testing, the throttle system of the tug was replaced as a precautionary measure by the airline.
During the course of the investigation, it was found that the tug had been involved in a previous incident where an aircraft was damaged. A report of the previous incident was obtained. The driver of the tug during the previous incident reported that the tug lurched when he was attempting to move the tug into position to connect to the aircraft.

PROBABLE CAUSE: "The partial failure of the aircraft tug for undetermined reasons."

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: CHI01FA129
Status: Investigation completed
Duration: 1 year and 2 months
Download report: Final report

Sources:

NTSB

History of this aircraft

Other occurrences involving this aircraft
20 January 1972 N9333 Hughes Airwest 0 Las Vegas-McCarran International Airport, NV (LAS) non
1 April 1976 N9333 Hughes Airwest 0 near Spokane International Airport, WA non
Near miss

Location

Revision history:

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